ELECTRORHEOLOGICAL EFFECT OF CONDUCTIVE POLYMERS DISPERSED IN LIQUID CRYSTALLINE MATRIX

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1135-1141 ◽  
Author(s):  
MONIKA CISZEWSKA ◽  
JANUSZ PLOCHARSKI
Keyword(s):  
Liquid Crystalline ◽  
Silicone Oil ◽  
Crystalline Polymer ◽  
Electrorheological Fluids ◽  
Flow Curves ◽  
Homogeneous Solutions ◽  
Electrorheological Effect ◽  
Active Liquid ◽  
Er Fluids ◽  
Crystalline Matrix

Hybrid electrorheological fluids comprising powdered conjugated polymers dispersed in solutions of a liquid crystalline polymer were prepared and studied. FeCl 3 doped poly(p-phenylene) and pyrolised polyacrylonitrile were chosen as the dispersed phase and poly(n-hexyl isocyanate) dissolved in xylene was used as the active liquid matrix. All the component materials were extensively characterized by various methods. Flow curves of the hybrid ER fluids were recorded under electric field and compared with analogous curves obtained for dispersions of the powders in silicone oil and with homogeneous solutions of the LC polymer in xylene. A very significant enhancement of the ER effect in the studied hybrid fluids was observed.

INFLUENCE OF SURFACTANTS ON PROPERTIES OF ELECTRORHEOLOGICAL FLUIDS CONTAINING POLYANILINE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2461-2467 ◽  
Author(s):  
MAŁGORZATA BOCIŃSKA ◽  
HENRYK WYCIŚLIK ◽  
MARCIN OSUCHOWSKI ◽  
JANUSZ PŁOCHARSKI
Keyword(s):  
Yield Stress ◽  
Current Density ◽  
Silicone Oil ◽  
Flow Curves ◽  
Different Types ◽  
Order Of Magnitude ◽  
Dynamic Yield ◽  
Rate Of Sedimentation ◽  
Er Fluids

Sedimentation which is a natural process in most of ER fluids can be reduced by addition of surfactants that influence also other properties of the fluids. To study both the ER effect and the rate of sedimentation was the aim of the investigations. The ER fluids comprised powdered polyaniline and silicone oil to which surfactants of different polarity were added. The rate of sedimentation was measured by a sedimentation balance. The flow curves were recorded under electric field up to 2.5 kV/mm. Current density was also measured as a function of shear rate. It was found that the activity of a surfactant depends strongly on its polarity. The lipophylic surfactants stabilized the suspension very well but about 30% decrease of the dynamic yield stress was observed. The current density was reduced as well by almost one order of magnitude. The hydrophylic surfactants hardly stabilized the suspension but increase of yield stress was observed that was not followed by increase of current density. The role of different types of non-ionic surfactants was discussed.

A Novel Mechanism of Electrorheological Effect in Polymer Blends

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1983-1989 ◽  
Author(s):  
H. Kito ◽  
K. Tajiri ◽  
H. Orihara ◽  
Y. Ishibashi ◽  
M. Doi ◽  
...  
Keyword(s):  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
High Viscosity ◽  
Thin Layers ◽  
The Other ◽  
Parallel Plates ◽  
Low Viscosity ◽  
Electrorheological Effect ◽  
Er Fluid

We present a novel mechanism of an electrorheological (ER) effect found in a polymer blend of a liquid crystalline polymer (LCP) with high viscosity and a polydimethylsiloxane (DMS) with low viscosity. In this type of ER fluid thin layers of DMS are formed between the parallel plates of a viscometer and so the blends separated by them can slide on each other, resulting in the decrease of the apparent viscosity. Under an electric field, on the other hand, the area of the layers decreases and thus the ER effect appears.

Review of the Electrorheological (Er) Effect of Polyurethane-based Er Fluids

2008 ◽  
Vol 18 (2) ◽  
pp. 23956-1-23956-8 ◽  
Author(s):  
S. Schneider ◽  
S. Eibl
Keyword(s):  
Silicone Oil ◽  
Molecular Size ◽  
Electrorheological Fluids ◽  
Chemical Analyses ◽  
Temperature Dependent ◽  
Polarization Model ◽  
Basic Principles ◽  
Dependent Behavior ◽  
Er Fluids ◽  
Temperature Dependent Behavior

Abstract Electrorheological fluids (ERF) change viscosity when an electric field is applied. A special type of ERF consists of polyurethane particles which are doped with Li+ and /or Zn2+ cations and suspended in silicone oil. This article gives an overview of the temperature dependent behavior of the ER effect for these fluids and describes the basic principles how this is explained. Chemical analyses provide information as a basis for a polarization model in several dimensions down to molecular size.

ELECTROSTATIC INTERACTIONS FOR PARTICLE ARRAYS IN ELECTRORHEOLOGICAL FLUIDS II: MEASUREMENTS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2895-2902 ◽  
Author(s):  
YING CHEN ◽  
H. CONRAD
Keyword(s):  
Shear Modulus ◽  
Electric Field ◽  
Shear Strain ◽  
Enhancement Factor ◽  
Shear Force ◽  
Electrostatic Interactions ◽  
Silicone Oil ◽  
Electrorheological Fluids ◽  
Proportionality Constant ◽  
Er Fluids

The force required to shear one-, two- and three-chain clusters of 230 µm dia. glass beads in silicone oil was measured. In each case the shear force was proportional to the shear strain, the proportionality constant increasing with electric field and number n of chains in the cluster. The derived shear modulus G also increased with n. An extrapolation of the present results suggests that a cluster of 4–5 chains would give the stress enhancement factor of 10–20 observed for real ER fluids.

scholarly journals Electrorheological Effect of Liquid Crystalline Polymer

1995 ◽  
Vol 23 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Akio INOUE ◽  
Syunji MANIWA ◽  
Tomio SATOH ◽  
Keiko TANIGUCHI
Keyword(s):  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Electrorheological Effect

Carbon Nanotubes-Adsorbed Polymeric Microspheres for Electrorheological Fluids

2006 ◽  
Vol 321-323 ◽  
pp. 917-920 ◽  
Author(s):  
Seok Ho Yoon ◽  
Hyoung Jin Choi ◽  
Hyoung Joon Jin
Keyword(s):  
Carbon Nanotubes ◽  
Colloidal Solution ◽  
Silicone Oil ◽  
Electrorheological Fluids ◽  
Polymeric Microspheres ◽  
Composite Microspheres ◽  
Pmma Microsphere ◽  
Conductivity Range ◽  
A Chain ◽  
Er Fluids

Surface-conductive microspheres consisting of poly(methyl methacrylate) (PMMA) (6.5 μm) core and carbon nanotubes (CNTs)-adsorbed shell were prepared using a simple process involving the blending of two colloidal solution; an aqueous CNT dispersion with surfactants and an aqueous PMMA microsphere colloid. These were adopted as the suspended particles for electrorheological (ER) fluids, in which the electrical conductivity originated primarily from the surface-coated conducting CNT layers. The CNT-adsorbed polymeric microspheres were monodisperse and spherical in shape. The CNT-PMMA composite suspensions in silicone oil showed the typical ER characteristics of forming a chain-like structure under an applied electric field. The CNT-PMMA composite microspheres exhibited a conductivity ranging from 5.2×10-4 to 6.3×10-5 S/cm, which is an acceptable conductivity range for ER fluids. This phenomenon can be explained by the interfacial polarizability of CNTs adsorbed on the surface of the polymeric microspheres.

Investigation of Thermal Conductivity of Alumina/Silicone Oil Electrorheological Fluids

2010 ◽  
Vol 129-131 ◽  
pp. 421-425 ◽  
Author(s):  
Yi Chun Wang ◽  
Xiao Xia Sun ◽  
Xiao Rong Tang ◽  
Fa Cheng Wang
Keyword(s):  
Thermal Conductivity ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Silicone Oil ◽  
Conductivity Measurement ◽  
Electrorheological Fluids ◽  
High Voltage Power Supply ◽  
Heating Device ◽  
Er Fluids

Electrorheological (ER) fluids are new materials with good properties such as dielectric constant, dielectric loss or conductivity, which display remarkable rheological behavior, being able to convert rapidly and repeatedly from a liquid to solid when an electric field is applied or removed. In this study, suspensions of alumina (A) were prepared in silicone oil (SO). The effects of electric field strength and temperature of the suspensions on thermal conductivity were determined. Thermal conductivity measurement in different conditions was carried out via experimental instrument with high-voltage power supply and water heating device to investigate the effects of electric field strength and temperature on ER performance and thermal conductivity. The results show that the thermal conductivity is in accordance with ER properties enhanced by increasing the field strength and decreasing the temperature.

THE CONDUCTIVITY AND TEMPERATURE DEPENDENCE OF BATIO3 COATED- PAN BASED ELECTRORHEOLOGICAL FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1423-1429 ◽  
Author(s):  
J. H. WEI ◽  
J. SHI ◽  
Z. Y. LIU ◽  
J. G. GUAN ◽  
R. Z. YUAN
Keyword(s):  
Shear Stress ◽  
Barium Titanate ◽  
Silicone Oil ◽  
Sol Gel ◽  
Temperature Stability ◽  
Electrorheological Fluids ◽  
Environment Temperature ◽  
Er Fluids ◽  
Favorable Temperature ◽  
Gel Processing

Coated-PAn particles consisting of polyaniline(PAn) core and barium titanate ( BaTiO 3) shell were synthesized by modified sol-gel processing. The shear stress and current density of the suspensions of Coated-PAn particles and pure PAn particles in silicone oil with a 20vol% were investigated at different conductivity and environment temperature. The dielectric and the conductance behavior of coated PAn particles as a function of temperature we also investigated. The results showed that the ER effect of BaTiO 3 coated PAn particles was far stronger than that of pure polyaniline synthesized by the same method. Meanwhile, the BaTiO 3 coated-PAn particles also showed favorable temperature stability and low current loss at the high electric field, which is rather important for the ER fluids application.

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